The battle to save the Arabian sand gazelle

Scientists are working to increase the genetic biodiversity of the Arabian sand gazelle.

The numbers of Arabian sand gazelle have increased but there are concerns over inbreeding causing harmful recessive traits. Karim Sahib / AFP
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With its slim body and beautifully curved horns, the Arabian sand gazelle is nothing if not an elegant creature.

But for all its majesty, it is actually one of the animals classed as vulnerable by the International Union for the Conservation of Nature.

Although the goitered or black-tailed gazelle, of which it is a subspecies, can be found more widely the Arabian sand gazelle exists only on the Arabian Peninsula in, among other places, the sandy deserts in the south-east of Abu Dhabi emirate.

The long-term future of this animal has been the subject of concern for decades and until 2008 its numbers were in decline, but conservation efforts have led to a growth in the population.

Locally there are now said to be about 50,000 and, if current growth rates were to continue, the tally could increase by tens of thousands in the years to come.

However, the conservation ­efforts have brought a new ­problem.

Many of these creatures are not wild but are kept in managed ­areas and this, alongside rapid growth in numbers from a smaller population base, creates a risk of inbreeding. There is even a chance that full or half siblings could mate with one another.

Inbreeding often leads to the emergence of harmful recessive traits that, in more ­genetically diverse animals, tend to be masked by dominant forms of genes.

Scientists have described the phenomenon of “inbreeding ­depression”, which can reduce the fitness of individuals and can lower fertility rates, potentially threatening the long-term ­survival of populations.

To help prevent such problems, the Environment Agency Abu Dhabi carried out a comprehensive genetic study of the Arabian sand gazelle in the emirate.

“We have huge captive-breeding programmes in the UAE,” said Jamal Al Zaidaneen, project manager, terrestrial and marine biodiversity at Ead.

“If we carry on without considering the genetic management, we are maybe going to manage it in an improper way.

“We have to make sure we’re managing the genetic material to save the genetic biodiversity.

“We need to make sure the population we’re managing is containing the best individuals from a genetic perspective to conserve the real value.

“We have to manage the quality of the population, not only the quantity.”

The project began in 2014. At 21 locations in Abu Dhabi where the Arabian sand gazelle is found, blood samples were taken from 20 animals.

These individuals were also assessed for their morphological traits or physical characteristics, such as the length of the body and of the horns.

The colour of the coat was among the variables ­recorded, and pictures of each of the animals being studied were taken.

The Ead’s laboratories extracted DNA from the blood samples. Not all of the samples allowed for a suitable DNA extraction, so the total number of DNA samples generated was 380. These were sent for analysis to Floragenex, a laboratory in Oregon in the US.

This allowed for the identification of genetic markers – ­variations in the sequence of an organism’s DNA that can correlate with differences in the characteristics of individuals.

Examples of these differences include what are known as single nucleotide polymorphisms.

DNA is made up of strands of nucleotides, which determine which proteins are produced by genes. There are four nucleotides, adenine (A), cytosine (C), guanine (G) and thymine (T), a sequence of three of which codes for a single amino acid, the building block of proteins.

As the name suggests, a single nucleotide polymorphism is a difference between individuals in the type of nucleotide found at one position in the DNA.

By identifying genetic markers, researchers can highlight which sand gazelles have particular types of genetic variation that could be transferred to other populations in Abu Dhabi.

“We can identify in this ­location that we have the highest diversity and we need to invest in this place,” said Mr Al ­Zaidaneen.

“This location can act as a source to other populations – to bring new blood to other locations. It’s not only quantitative; it can give you qualitative values to direct your management.”

Carried out in partnership with Barari Forest Management, which manages most of Abu Dhabi’s forests, the project has been a success, said Mr Al Zaidaneen. It has, for the first time, identified site-specific genetic variation in the animals and the results indicate that, so far, there has not been any loss of genetic variation across populations, so inbreeding is not yet become a major concern.

However, Mr Al Zaidaneen ­cautioned that inbreeding could become a problem because the level of heterozygosity – having different forms of a particular gene on each one of a pair of chromosomes – is “low to moderate”.

As well as being useful for future breeding programmes, the information could help researchers to better understand the evolutionary history of the animals and shed light on pedigrees.

The genetic markers identified in this research could also be used to help understand variation in Arabian sand gazelle populations elsewhere.

“These markers are like a scale that can, for the future, be a benchmark for most of the genetic diversity for other populations, like in Saudi Arabia,” said Mr Al Zaidaneen, a Jordanian who, before joining the Ead and moving to the UAE, worked on conservation efforts in his home country.

Now that the Arabian sand gazelle project has been completed, Ead is planning to carry out similar studies of the genetic variation of the Arabian mountain gazelle (Gazella gazella cora) and Arabian oryx (Oryx leucoryx).

“These are indigenous species for the country and they’re part of the heritage established by the late Sheikh Zayed,” said Mr Al Zaidaneen, referring to the Founding Father.